I’m lazy, so will just reprint something I posted on another forum. I’m 66 now, crossed in 1993, and these are some thoughts that have come out of that. Though I’ve not addressed your questions directly, you may find answers to some you didn’t ask.
First of all, remember this important thing: There can be only one "first time". You'll never forget it, so make it the best adventure you can possibly manage. Ride your dream, not someone else’s tried-and-true route. Pore over the maps and choose a path that speaks to you. Extend yourself--don't plan all the "surprise" out of it. Don't, for example, make reservations ahead, or promise to visit people who live along the way. Live in the unknown. The object, I think, should be to immerse yourself in the unfamiliar to the point of feeling vaguely lost--a bit vulnerable and dependent on your own common sense and resources more than you may ever have been. If you can possibly carry camping and cooking gear, do it. It may feel scary at first, but not knowing, when you rise each morning, where you'll sleep that night is exhilarating in itself. When you want “civilized”, seek out the small-town restaurants that the locals frequent; stay at the mom-and-pop, “neon” motels. Do everything you can to force those pores open and sharpen your five senses. Do that and you'll be surprised by how you'll remember the smallest detail years hence, still feel a sense of ownership of that narrow ribbon of asphalt whose last mile will have separated you forever from that rider who pedaled the first one. Make it “your” road, not someone else’s fast-food, chain-lodging road. But never forget that as you clock off each mile you travel as a guest, not an owner. “Please” and “thank you” are magic to the ears of the tourist-weary shopkeeper. You’ll remember many a person who made your day out there, so make theirs, too, and may all your memories be good ones.
Some details I might mention:
CARGO. I like panniers. There are many who prefer trailers (Google “bike trailers”), but I keep thinking of loss of maneuverability, difficulty parking, less stability on steep descents, wider footprint (in traffic)--things like that. I use both front and rear panniers plus a handlebar bag. Roomy with good weight distribution. Feels like the natural state after a few days out.
Don’t take too much stuff, especially food. Grocery stores are everywhere except in the longest lonely stretches where you can stock up just before.
WATER. It’s nice to have 3 bottle cages. In most areas, I don’t fill the 3rd one; it’s there when supply is iffy and at the last water stop of the day before searching for a campsite. Carry extra web straps for general purposes, including lashing store-bought gallons of water before entering the desert.
EATING OUT: breakfast is my favorite, because more locals show up--especially those who aren’t in a hurry and can “sit a spell”. Lots of conversations start with the morning coffee klatch. Even if I cook breakfast in camp, I always seem to end up having another one, just for the human contact.
FENDERS: have them. Ditto, rain gear. BIG ditto: REARVIEW MIRROR (I like the helmet-mounted ones.)
ROUTE PLANNING. It’s ok to map out your route meticulously. As long as it’s along roads you’ve never traveled, you lose no sense of adventure by writing down road names. The advantage is that when you’re on the road, pre-drawn route frees you from too-frequent map reading and allows you to look at what you’re passing through instead.
PRIVACY. Traveling with others: try to have a lot of “alone” time on the road--where you can’t see your companions. Try to mimic solo riding on some days, agreeing to meet at the day’s destination or at some rendezvous point along the way.
NOTE TAKING. I like hanging a lightweight mini-tape recorder around my neck so I can make notes while I ride.
PHOTOS. I took a lot of scenic shots, but I regret not taking pics of people met casually--shopkeepers, etc. As I mentioned earlier, you will remember more than you might expect, so it would be nice to have photos to bring back the faces.
Use web straps, not bungee cords, to tie down stuff on back rack. Bungees have too much give; you'll waste energy in overcoming bounce and side-to-side thrashing.
TRIAL RUN. Before you leave, consider a trial run. A short, one-night shakedown trip, followed later by a 3-night, 150-mile mini tour, camping in a different place each night, will allow you to discover and correct most of the bugs you'd have encountered on the real trip.
RAIN. Loaded with gear, ride for a day in the rain beforehand. The sooner the better to find what needs waterproofing.
EQUIPMENT MAINTENANCE. Learn to dismantle, clean and reassemble your camp stove. BIG DITTO: learn to fix your own flats. If you’ve never done it, use an ice pick on your tire if you must, but go through the process once to make sure you’re able. ALSO....get a chain tool and learn to use it by opening a link and then reclosing it. Then carry a spare link on the road. A guy in a pickup can maybe fix a flat for you, but if your chain breaks, you’re helpless without a tool. FINALLY...the same goes for cables. Learn to replace both brake and shifter cables. Carry spares.
TENTS. I think one-person tents are preferable to larger ones. The privacy is good, everyone sleeps better, and if your partner drops out mid-trip, you’re not left lugging a house.
DRY TENT. Buy a good tent, capable of remaining dry in a prolonged downpour. You'll be toasty warm in the always-DRY SLEEPING BAG that you unpack and repack inside the dry tent. A dry tent allows you to choose a down bag if you want (pounds saved.) OVERHANG or VESTIBULE is important so rain doesn't fall through the front door. If it's raining when you want to leave, pack everything while inside tent. Get into rain clothes. Then strike the tent & stuff into its bag quickly. Try to keep fly deployed. Stuff the mostly-dry tent under the fly, then shake & stuff the wet fly.
CAMPSITES: State campgrounds are generally great, and you'll often avoid much of the leviathan-RV crowd. National forest campsites are good, too, though often quite primitive. The latter are often unmanned, so be sure to have lots of ones and fives to make exact change when you stuff your fee into the box at the gate. (Nat'l forest sites do take personal checks.) And yes, church and school yards and even town parks are fair game if you ask first. Try to return the favor, though, by patronizing a local restaurant or making a small donation. It's also fun to bivouac. I avoid private property but have pitched many times in non-posted, wooded areas of public property--thickly-treed road medians and the like. It's part of the adventure, and when you really don't know where you'll end up at the end of the day, bivouacking is a common necessity.
Carry your own TIRE PUMP and PATCH KIT. I prefer a full-size pump to the compact models, as it's easier to use. Since you'll be topping off each morning, the extra weight is worth it.
TOOLS. Make sure you have a tool for every adjustment you may need to make. I draw the line at the heavier tools, though--crescent wrench, crank extractor, freewheel remover--and plan instead to just sit by the roadside and cry, waiting for the inevitable pickup to come along.
FOOD. Carry a bit of emergency ration, but don't carry too much food. Shop daily. It's fun to patronize a lonely little mom-and-pop grocery, and they can use the business. They are often as hungry for a chance to chat as you are for the food, and you may easily be their day's high point, what with your incredible story of a cross-country ride. They're one-of-a-kind, and that's what you're after, isn't it? Me? I dine down-and-dirty when I camp. Food preparation is low on my list of fun things, so I often just get a can of good stew or chili and boil it unopened for 10 minutes, immersed in a 1 qt aluminum pot of water. I turn the stove off and let the whole thing rest 15 minutes before opening, and then eat right out of the can so there's only a spoon to wash. A can of fruit and a slice of bread--that's my dinner. I get my nutritional balance back at breakfast or lunch, when I'm not tired from the day's ride. Don't overworry about food. Do what Mark Twain advised: "Eat what you like and let the food fight it out inside."
CLOTHING. I carry an extra jersey and cycling shorts. One polypropylene long-john pants and one lycra tights. One polypro turtleneck. One rain jacket, pants and lightweight overshoe. One balaclava. Two sock and two glove liners, all polypro. Two pair wool socks, one cotton. One lightweight sleeping shorts and t-shirt. Two cycling gloves plus one warm, fingered pair cycling gloves. I live in the cycling clothes.
LAUNDRY. At a coin laundry, just get into your rain suit and wash everything else. Go easy on the dryer temperature; check often. In camp with running water, I just hand-wash things in the sink or shower using bar soap, and dry them the next day in a lightweight net on my back rack.
WILD ANIMALS. I tend not to camp alone in bear country, and especially not in mountain lion country. Go with your own preference, though, but be sure not to contaminate your bike bags, clothing or tent with food odors. Wash all bags before embarking, and don't carry anything that might ooze or spill or otherwise smell up your bags. I carry fig bars, for example, in a tightly-capped Rubbermaid bottle. Same with raisins and nuts. Never have food in your tent. Once in there, it may leave residual odors which can attract animals long afterward. At night, suspend food from a tree branch (see literature for pointers).
Bottom line: be less concerned about what might happen than about what might NOT happen. In other words, make it the best adventure ever. Have fun, and the best of luck to you.....Lew